Indicator for incandescent lamps



Nov 12, 1935. H. H. HELMBRIGHT 2,021,062

INDICATOR FOR INCANDESCENT LAMPS Filed Dec. 9, 1952 lnvezhcor Hnry H. Helmbrjght,

H is Att orney.

Patented Nov. 12, 1935' 2,021,062 INDICATOR FOR INCANDESOENT LAMPS Helmbright, Cleveland Heights, Ohio,

General Electric Company, a corporation of New York December 9, 1932, Serial No. 646,463

2 Claims. (01. 117-311 Henry H.

assignor to Application The present invention relates to indicators for incandescent lamps for indicating when a lamp burns out. One application of the invention is in connection with series incandescent lamp circuits for indicating which of the several lamps of a string is burned out ing. It is to be understood, however, that the invention is not limited necessarily to use in series circuits as it may be used wherever found applicable.

The object of my invention is to provide an improved indicator of the above referred to type, and for a consideration of what I believe to be novel and my invention, attention is directed to the following specification and the claims appended thereto.

In the drawing, wherein I have illustrated one embodiment of my invention, Fig. 1 is a side view of an incandescent lamp having an indicator embodying my invention attached thereto; Fig. 2 is a vertical sectional view through the indicator structure; Fig. 3 is a top plan view, partly in section, of the structure shown in Fig. 2, and Fig. 4 is a diagrammatic view showing indicators applied to a series lighting circuit.

According to the embodiment of my invention shown in the drawing-I provide an indicator which comprises an adapter which fits between the incandescent lamp and its socket forming a unitary part thereof when the incandescent lamp is in its socket and which carries indicating means comprising preferably a small vapor lamp, for exconnected in series with a ample a neon lamp, resistance of high value, the vapor lamp and resistance being in turn connected in shunt to the incandescent lamp filament. As is known, a vaper lamp, such as a neon lamp, is rendered luminous by a relatively small amount of current.

As shown particularly in Figs. 2 and 3, the adapter comprises a metal shell 8 which has one end 2 corrugated as indicated to provide threads into which the shell on the end of an incandescent lamp may be screwed, and which has the other end 3 corrugated as indicated to provide threads adapted to'screw into a standard lamp pocket.

Connected to the upper portion of shell I is an ine sulating structure comprising in the present in stance two insulating members 4 and 4 connected by a screw 5 which serves to connect an inner contact 6 with an outer contact 1.

Insulating member 4 may comprise a suitable compound into which the edge of shell end 3 is molded and insulating member 4 may comprise a suitably shaped block of porcelain or similar material held in position against insulating memwhen the lamps cease burnmay be viewed it being PATENT OFFICE her 4 by screw 5. Inner contact 6 forms a nut for screw 5 and is held in position by the screw. Outer contact I may be held by having an edge molded into insulating member 4.

When the adapter is screwed into a lamp socket, 6 the outer contact I makes contact with the central contact of the socket and when an incandescent lampis screwed into the adapter, its central contact engages the central contact 6 of the adapter. The shell I forms the other terminal, 0 being in electrical engagement with the shell of the socket and the shell of the lamp.

Surrounding the lower portion of shell 2 and. suitably united thereto is a ring 8 of suitable insulating material such as a suitable molding compound. Ring 8 is provided with two transversely extending openings 9 and Ill. Located in opening 9 is a suitable resistance H of high value. Located in opening Ill is a. small vapor lamp l2, such as a neon lamp, which is rendered luminous by a relatively small amount of current. The resistance II and vapor lamp I2 may be fastened in place by a suitable sealing compound as indicated at l3. In ring 8 in line with vapor lamp l2 are openings l4 and i5 through which the lamp thus visible from a plurality of points. Lamp I! has one terminal connected to shell I by conductor l6 and the other terminal connected to one terminal of resistance H by a conductor II. The other terminal of resistance ll is connected by a conductor 18 to central terminal 6. With this arrangement it will be clear that when an incandescent lamp is screwed into the adapter, and the adapter is threaded into a socket, the vapor lamp l2 and resistance H are connected in shunt to the incandescent lamp filament. This is shown diagrammatically in Fig. 4.

In Fig. 1, an incandescent lamp I9 is shown as having a base including a shell 20 which is threaded into the adapter, the adapter thus forming in substance a part of the lamp. The upper end 3 of the adapter is threaded into a lamp socket 2| by screwing the portion 3 of the adapter into the socket shell 22. 45

Fig. 4shows a series lighting circuit in which a series of incandescent lamps l9- are each provided with an adapter embodying my invention connected in shunt thereto. Resistances II are of such high value that during normal operation only negligible current flows through them and the vapor lamp in series therewith, the current being insuflicient to cause the lamp .to glow. In case one of the'lamps I9 burns out, the series circuit is opened and all the lamps go out. In

and the socket,

the case of the burned outlamp, theresistance and the glow lamp which are in shunt with the burned out lamp will be connected directly in I by the glow of the vapor lamp which incandescent lamp is burned out and can replace the same. By means of the plurality of openings I4 and I5, the vapor lamp is visible from a number of points, a thing of great convenience in actual practice in detecting the burned out lam It will be seen that the adapter is simple in structure comprising few parts, and can be manufactured at low cost. Also, it is simple to use, being adapted for use in connection with standard lamps and sockets now in use. This is an important consideration.

While I have shown my indicator as embodied in an adapter built as a separate structure adaptel to be located between an incandescent lamp it is to be understood that my invention is not limited to this arrangement necessarily and that the indicator may be construct-'- ed as a unitary part of either the incandescent lamp or its socket. 7

What I claim as new and desire to secure by Letters Patent in the United States is:

shell being adapted to be connected to a lamp socket and the other end being adapted to have 5 an incandescent lamp connected thereto, a. member carried by the shell and having an opening therein, a vapor lamp mounted in said opening, said member being provided with one or more passages through which the lamp is visible, and [0 a resistance carried by the memmr, said resistance and vapor lamp being connected in series with each other to the shell and central contact.

2. An indicator for an electrical device comprising a threaded shell provided with a center 15 contact insulated from the shell at one end there HENRY H. HELMBRIGHT. 

